Atomizing and/or vaporizing a liquid in a gas stream is often necessary in high purity fluid processing applications. For example, these processes may be employed to deposit high-purity, metal oxide films on a substrate. Moreover, the liquid mixtures may also be utilized for spray coating, spin coating and sol-gel deposition of materials. In particular, chemical vapor deposition (CVD) is an increasingly utilized high purity fluid delivery process for forming solid materials, such as coatings or powders by way of reactants in a vapor phase. Typically, a reactant vapor is created by heating a liquid to an appropriate temperature and bubbling a flow of carrier gas through the liquid (i.e. high purity fluid stream) to transport the vapor into a CVD chamber. Specifically, a gas stream and liquid stream are introduced into a single channel or conduit at a T-junction. The CVD system pumps a fluid stream at a steady, controlled rate into a hot region which may include ultrasonic energy for effecting the mixture components. However, this technique creates a large dead volume of material upon discontinuance of the process. Further, bubbling can often be an unpredictable method of vaporization, in which the precise quantity of the liquid reactant is difficult to control.
Typically, an integrated fluid and vapor delivery system is comprised of a liquid flow controller and a vaporizer and a vapor outlet manifold. The liquid flow controller calibration and response procedure conducted within the manufacturing procedure for the controller is designed to optimize the delivery and response times of liquid delivery (not downstream vapor delivery performance). It has been presumed in the industry that adequate calibration and response of liquid flow by the liquid flow controller is sufficient to provide optimized performance of vapor delivery in an integrated liquid and vapor delivery system. However, while adequate liquid flow control is necessary, it is not sufficient to optimize vapor delivery performance. Thus, there is a need for an integrated fluid and vapor delivery system design that does sufficiently optimize vapor delivery.
Accordingly, there is a need for an atomizer which predictably atomizes a fluid while virtually eliminating dead volume upon discontinuance of the atomization process.